Obesity is associated with chronic diseases such as diabetes as well as higher healthcare costs. However, some studiesf have found that obesity may actually be protective during critical illness. There are no large studies on obesity and long-term outcomes after ICU hospitalization or comparing outcomes of obese patients with and without chronic conditions.

We are using MIT's MIMIC-II database containing de-identified data on over 19,000 adult ICU patients. We mapped lab and other variables to standard vocabularies, e.g. LOINC, in order to analyze comparable data, and we used natural language processing to retrieve unstructured data.

Initial survival analysis using the Cox proportional hazard model of over 12,000 ICU subjects shows that after adjusting for age, gender, initial SAPS score, first ICU service, mechanical ventilation, and diabetes, obesity and overweight are protective during and after critical illness. Compared to the normal weight group, overweight, obese, and underweight patients had 0.75, 0.76, and 1.47 times the hazard of death a year after their last hospitalization (p < 0.0001), with a similar pattern for in-hospital mortality. Age, SAPS score, and ICU service were also predictive. We expect our results to be even more robust after adding additional data and covariates.